Lokkaite-(Y) is a rare yttrium-rich carbonate mineral typically occurring as thin, platy crystals or fine-grained aggregates in pegmatitic environments. It is a secondary mineral formed through the alteration of other yttrium-bearing minerals, often appearing as coatings or encrustations on host rock surfaces.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Semitransparent

mineralrare

Lokkaite-(Y)

Hardness: 3
Luster: Vitreous
Streak: White
Transparency: Semitransparent

Is this lokkaite-(y)?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch lokkaite-(y) with a known reference. Lokkaite-(Y) sits at Mohs 3, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: snow white.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: aggregates, radial.

Often confused with

Lokkaite-(Y) vs. its common look-alikes, and how to tell them apart in the field.

mineral

Tengerite-(Y)

Mohs 3.5

How to tell apart: Luster reads vitreous on Lokkaite-(Y) and dull, chalky on Tengerite-(Y).

All properties

Chemical formula: CaY₄(CO₃)₇·9H₂O
Mohs hardness: 3
Density: 2.92 g/cm³
Colors: Snow white
Streak: White
Luster: Vitreous
Transparency: Semitransparent
Crystal system: Orthorhombic
Crystal habit: Aggregates, radial
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: A secondary mineral formed by alteration of primary rare-earth minerals

Where rockhounds find lokkaite-(y)

Classic worldwide localities

Pyörönmaa pegmatite, Kangasala, Finland
Ytterby, on Resarö Island, near Vaxholm, and in the Åskagen pegmatite quarry, Värmland, Sweden
Kirigo and Yokatake, Higashi Matsuura district, Saga Prefecture, and at Lisaka, Date district, Fukushima Prefecture, Japan
Evans-Lou quarry, near Hull, Quebec, Canada

Field-hunting tip

Where it forms: A secondary mineral formed by alteration of primary rare-earth minerals. If you start seeing tengerite-, lanthanite, kimuraite- in float, you are in the right ground. Typical habit: aggregates, radial. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify lokkaite-(y)?+

Mohs hardness is 3. Luster: vitreous. The streak is white. Common colors include snow white.

Where is lokkaite-(y) found?+

Notable localities include Pyörönmaa pegmatite, Kangasala, Finland; Ytterby, on Resarö Island, near Vaxholm, and in the Åskagen pegmatite quarry, Värmland, Sweden; Kirigo and Yokatake, Higashi Matsuura district, Saga Prefecture, and at Lisaka, Date district, Fukushima Prefecture, Japan; Evans-Lou quarry, near Hull, Quebec, Canada.

Is lokkaite-(y) safe to handle?+

Contains rare earth elements and is radioactive; handle with care and wash hands after contact to prevent ingestion or inhalation of dust.

What rocks look like lokkaite-(y)?+

Lokkaite-(Y) is most often confused with Tengerite-(Y), Calcite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with lokkaite-(y)?+

Lokkaite-(Y) commonly co-occurs with Tengerite-, Lanthanite, Kimuraite-. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does lokkaite-(y) form in?+

Where it forms: A secondary mineral formed by alteration of primary rare-earth minerals. Working float back to the host body is the standard way to chase a fresh occurrence.

What is lokkaite-(y) used for?+

Lokkaite-(Y) is used in collector.

Find lokkaite-(y) on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.